In-Order Packet Delivery During Wireless Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During wireless communication handover, data packets are often delivered out-of-order due to re-transmissions and lack of sequencing information, leading to inefficiencies in packet ordering and decoding at target base stations.
Innovation Solution
The method involves determining the last consecutive packet received by a source base station and identifying missing packets by transmitting an index of the last packet received in-order from the source or mobile device to the target base station, allowing the target station to wait for and re-order packets accordingly before decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ re-transmission is used to ensure packet delivery, then reliability of packet delivery is improved, but packets are delivered out-of-order causing sequencing problems at target base station
Solution Approach 1:
The source base station performs preliminary actions by determining the index of the last in-order packet before handover and proactively transmitting this indexing information to the target base station. This allows the target base station to have advance knowledge of the expected packet sequence, eliminating the need for complex re-ordering operations after handover and resolving the sequencing complexity problem while maintaining HARQ re-transmission reliability.
2Reliability
If packet re-ordering is performed at target base station, then in-order delivery is achieved, but processing time is increased due to waiting for missing packets
Solution Approach 1:
The target base station performs preliminary action by receiving and storing the index information of the last in-order packet from the source base station before actual packet reception begins. This pre-configured knowledge allows the target base station to immediately recognize and process packets in the correct sequence without waiting for missing packets or performing complex re-ordering operations, thus reducing packet processing time while maintaining in-order delivery.
Solution Approach 2:
The indexing information transmitted from source to target base station serves as feedback about the packet sequence state. This feedback mechanism enables the target base station to adjust its packet processing behavior accordingly, recognizing which packets to expect and in what order, thereby eliminating unnecessary waiting time and maintaining efficient in-order delivery.
3Device complexity
If indexing information is transmitted from source to target base station, then packet sequencing is simplified, but communication overhead is increased
Solution Approach 1:
The invention extracts only the essential indexing information (the index of the last in-order packet) from the complete packet data and transmits only this extracted information to the target base station. This selective extraction approach simplifies packet sequencing at the target base station while minimizing communication overhead by transmitting only the critical sequencing information rather than redundant data.
Data Source
AI summary
Systems and methodologies are described that facilitate processing service data units (SDU) in-order during communication handover in wireless networks. In particular, for mobile devices using re-transmission schemes, SDUs can be processed in-order by indicating to a target base station an index of a last SDU received in-order before handing off communication to the target base station. Additionally, SDUs received subsequent to one or more non-acknowledged SDUs can be forwarded to the target base station. Utilizing this information, the target base station can determine one or more SDUs the mobile device is preparing to re-transmit and can wait for this SDU before processing subsequently received SDUs. Also, a timer can be utilized to end a waiting period for the SDU.